Studies On The Lipid-lowing And Anti-oxidation Of Cranberry Extracts

Objective:To explore the effects of on the cranberry extracts’(CE) hypocholesterolemic and antioxidant effects on hypercholesterolemia-induced rats, and focus on CE’s ability to regulate lipid metabolism-related nuclear receptor proteins.Methods:50male SD rats, about120-130g weight, were randomly divided into5groups (10rats each group) namely:normal (control), hypercholesterolemic (model group), and3experimental groups given with high, medium and low dose CE. The normal group was given with normal basal diet, while the other4groups were given with high-fat diet to induce hypercholesterolemia. CE groups high, medium and low were given orally with1,0.1and0.01g/kg bw/d of CE, respectively, for8weeks.(1) After8weeks, the rats were euthanized and blood was collected intra-cardiac. The serum total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C) and alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) activity level were measured using BS-190automatic biochemical analyzer.(2) The liver was collected to measure organ coefficient and for biopsy and histopathology.(3) Liver homogenates were prepared to measure superoxide dismutase (SOD), lipid peroxide malondialdehyde (MDA) and glutathione peroxidase (GSH-PX), total antioxidant capacity (T-AOC), catalase (CAT) activities.(4) Tissue liver lysates were prepared for protein immunoblot (Western Blot) analysis of peroxisome proliferator-activated receptor a (PPARa), lipoprteinlipase (LPL), cholesterol7a-hydroxylase (CYP7A1) and liver X receptor (LXRa) protein expressions.Results:1.. The results showed that the weight of the hypercholesterolemic and3CE groups were significantly higher than the normal group (p<0.05). The liver organ coefficients of CE treated groups were lower than the model group, however decreased in medium dose of CE (p<0.05). Gross examination of the liver of the hypercholesterolemic group showed hepatomegaly, yellow-colored, blunt-edges, and brittle, while CE treated groups showed lesser degree of hepatomegaly and the liver color become reddish as the dose of CE increases. Histopathologic examination expressed that high-fat diet fed groups showed different degrees of fatty degeneration where CE significantly alleviated fatty degeneration and showed that CE dose and fatty degeneration had an inverse relationship.2、Serum biochemical index examination showed that TC, TG, and LDL-C of CE treated groups were significantly lower (p<0.05) than the hypercholesterolemic group. HDL-C of low CE dose was significantly increased (p<0.05) while there is no significantly change (p>0.05) in high CE dose group. Serum ALT, AST and ALP were lowed and showed significant difference (p<0.05) thus indicating a dose-dependent effect relationship.3、Antioxidant assays showed that, compared to hypercholesterolemic group, CE treated group had higher SOD, GSH-PX, and T-AOC activities while the MDA level was gradually decreased (p<0.05) thus indicating enhanced liver antioxidant system. However, the CE had not significant influence on liver CAT activity.4、Western blot results showed that low CE dose groups expressed increasing trend of PPARa expression and showed significant effect(p<0.05). The medium and high doses of CE raised the expression of LPL. Compared to the hypercholesterolemic group, the medium and high CE dose group showed highly significant CYP7A1(p<0.01) result while low CE dose did not show significant difference. Increasing expression of LXRa were shown in medium and high CE dose which were highly significant (p<0.01).Conclusion:Evaluation of serum TC, TG, LDL-C, HDL-C, ALT, AST, ALP, SOD, MDA, GSH PX, T-AOC, and CAT, established that cranberry extracts can reduce lipid accumulation in the liver, and can reduce the extent of oxidative damage. Furthermore, evaluation of PPARa, LPL, CYP7A1, and LXRa nuclear receptor protein expressions revealed that CE can reduce accumulation of cholesterol in the liver compared to the hypercholesterolemic group, thus, maintain cholesterol homeostasis.